Air conditioning, industrial chilling and power plant steam condensing systems are typically configured with arrays of tubes. Boilers and other commercial or industrial equipment may also include fluid tubes to provide various heat exchange functionality. Such tubes must be serviced to maintain efficient energy use, prevent or reduce fouling and corrosion and such servicing typically involves utilization of both mechanical and fluid treatment on the interior surfaces of the tubes. The fluid treatment itself often includes application of chemical cleaners or inhibitors. In some cases, different tools may be utilized for each of the mechanical agitation, chemical application, and powered fluid cleaning or washing.
One type of tool that may be utilized to effectuate mechanical agitation of tube deposits is a projectile that includes scraper blades, the projectile being forcibly passed (e.g., fired or shot) through a tube being serviced. Examples of tube scraper projectiles utilized in the tube cleaning industry are described in U.S. Pat. No. 5,305,488 issued to Lyle (“Lyle I”) and titled “TUBE CLEANING TOOL”, U.S. Pat. No. 7,454,812 issued to Lyle (“Lyle II”) and titled “TUBE CLEANING TOOL”.
Such projectiles generally include one or more scraper blades for scrapping the inside diameter of a tube or pipe and some mechanism for biasing the scraper blades against the inside walls of the tube or pipe. One typical mechanism for biasing the scraper blades (such as utilized in the Lyle I) includes a rubber bushing nested within or under the blades. Compression of the projectile assembly, e.g., by tightening a retaining nut, forces radial expansion of the rubber bushing, which applies increasing biasing forces on the scraper blades in an outward radial direction. Such typical projectiles, however, may suffer from various deficiencies.